day-night loop, dynamic skybox, clock on debug panel

res/shaders/skybox_gen.glslv

@@ -0,0 +1,10 @@
+#version 330 core
+
+layout (location = 0) in vec2 v_position;
+
+out vec2 v_coord;
+
+void main(){
+	v_coord = v_position;
+	gl_Position = vec4(v_position, 0.0, 1.0);
+}